The proposed research project will investigate if conformational differences occur in alpha- and gamma-crystallins of normal human lenses as a function of age. This will be done by absorption and circular dichroism measurements from 185 to 400 nm with emphasis on the near ultraviolet region. Low temperature absorption and circular dichroism measurements down to 77 degrees K will be utilized to enhance the resolution and reveal the differences. The same techniques will be used to find if there are conformational differences in the alpha- and gamma-cystallins among various cataractous lenses. Some of the biochemical and biophysical properties of human gamma-crystallins will be investigated. This will include amino acid analysis and titration of phenolic groups. Effects of concentration, ionic strength, pH, and temperature on the conformation will be monitored by absorption and circular dichroism measurements. The involvement of aromatic amino acids in the aggregational processes occurring with the alpha-crystallins will be studied by the same techniques. The yellowing of the human lens with age, which is concomitant with an increase in fluorescent pigments, will be monitored by fluorescence measurements. Since some of these pigments are covalently bound to the lens proteins, fluorescence measurements will be performed on normal and cataractous lens proteins. These measurements will yield information on the chemical properties of these fluorogens and whether they are involved in cataract formation.